winit-sonoma-fix/src/platform/linux/x11/util/wm.rs

use parking_lot::Mutex;

use super::*;

// This info is global to the window manager.
lazy_static! {
    static ref SUPPORTED_HINTS: Mutex<Vec<ffi::Atom>> = Mutex::new(Vec::with_capacity(0));
    static ref WM_NAME: Mutex<Option<String>> = Mutex::new(None);
}

pub fn hint_is_supported(hint: ffi::Atom) -> bool {
    (*SUPPORTED_HINTS.lock()).contains(&hint)
}

pub fn wm_name_is_one_of(names: &[&str]) -> bool {
    if let Some(ref name) = *WM_NAME.lock() {
        names.contains(&name.as_str())
    } else {
        false
    }
}

pub fn update_cached_wm_info(xconn: &Arc<XConnection>, root: ffi::Window) {
    *SUPPORTED_HINTS.lock() = self::get_supported_hints(xconn, root);
    *WM_NAME.lock() = self::get_wm_name(xconn, root);
}

fn get_supported_hints(xconn: &Arc<XConnection>, root: ffi::Window) -> Vec<ffi::Atom> {
    let supported_atom = unsafe { self::get_atom(xconn, b"_NET_SUPPORTED\0") }
        .expect("Failed to call XInternAtom (_NET_SUPPORTED)");
    unsafe {
        self::get_property(
            xconn,
            root,
            supported_atom,
            ffi::XA_ATOM,
        )
    }.unwrap_or_else(|_| Vec::with_capacity(0))
}

fn get_wm_name(xconn: &Arc<XConnection>, root: ffi::Window) -> Option<String> {
    let check_atom = unsafe { self::get_atom(xconn, b"_NET_SUPPORTING_WM_CHECK\0") }
        .expect("Failed to call XInternAtom (_NET_SUPPORTING_WM_CHECK)");
    let wm_name_atom = unsafe { self::get_atom(xconn, b"_NET_WM_NAME\0") }
        .expect("Failed to call XInternAtom (_NET_WM_NAME)");

    // Mutter/Muffin/Budgie doesn't have _NET_SUPPORTING_WM_CHECK in its _NET_SUPPORTED, despite
    // it working and being supported. This has been reported upstream, but due to the
    // inavailability of time machines, we'll just try to get _NET_SUPPORTING_WM_CHECK
    // regardless of whether or not the WM claims to support it.
    //
    // Blackbox 0.70 also incorrectly reports not supporting this, though that appears to be fixed
    // in 0.72.
    /*if !supported_hints.contains(&check_atom) {
        return None;
    }*/

    // IceWM (1.3.x and earlier) doesn't report supporting _NET_WM_NAME, but will nonetheless
    // provide us with a value for it. Note that the unofficial 1.4 fork of IceWM works fine.
    /*if !supported_hints.contains(&wm_name_atom) {
        return None;
    }*/

    // Of the WMs tested, only xmonad and dwm fail to provide a WM name.

    // Querying this property on the root window will give us the ID of a child window created by
    // the WM.
    let root_window_wm_check = {
        let result = unsafe {
            self::get_property(
                xconn,
                root,
                check_atom,
                ffi::XA_WINDOW,
            )
        };

        let wm_check = result
            .ok()
            .and_then(|wm_check| wm_check.get(0).cloned());

        if let Some(wm_check) = wm_check {
            wm_check
        } else {
            return None;
        }
    };

    // Querying the same property on the child window we were given, we should get this child
    // window's ID again.
    let child_window_wm_check = {
        let result = unsafe {
            self::get_property(
                xconn,
                root_window_wm_check,
                check_atom,
                ffi::XA_WINDOW,
            )
        };

        let wm_check = result
            .ok()
            .and_then(|wm_check| wm_check.get(0).cloned());

        if let Some(wm_check) = wm_check {
            wm_check
        } else {
            return None;
        }
    };

    // These values should be the same.
    if root_window_wm_check != child_window_wm_check {
        return None;
    }

    // All of that work gives us a window ID that we can get the WM name from.
    let wm_name = {
        let utf8_string_atom = unsafe { self::get_atom(xconn, b"UTF8_STRING\0") }
            .expect("Failed to call XInternAtom (UTF8_STRING)");

        let result = unsafe {
            self::get_property(
                xconn,
                root_window_wm_check,
                wm_name_atom,
                utf8_string_atom,
            )
        };

        // IceWM requires this. IceWM was also the only WM tested that returns a null-terminated
        // string. For more fun trivia, IceWM is also unique in including version and uname
        // information in this string (this means you'll have to be careful if you want to match
        // against it, though).
        // The unofficial 1.4 fork of IceWM still includes the extra details, but properly
        // returns a UTF8 string that isn't null-terminated.
        let no_utf8 = if let Err(ref err) = result {
            err.is_actual_property_type(ffi::XA_STRING)
        } else {
            false
        };

        if no_utf8 {
            unsafe {
                self::get_property(
                    xconn,
                    root_window_wm_check,
                    wm_name_atom,
                    ffi::XA_STRING,
                )
            }
        } else {
            result
        }
    }.ok();

    wm_name.and_then(|wm_name| String::from_utf8(wm_name).ok())
}